Is M23 a billable ICD-10-CM code?

No. M23 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does M23 sit in the tabular list?

Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Other joint disorders (M20-M25).

What cannot be coded together with M23?

M23 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

M23

M23 — Internal derangement of knee

Non-billable headerICD-10-CM

M23 is a non-billable header ICD-10-CM code for internal derangement of knee. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

ankylosis (M24.66)
deformity of knee (M21.-)
osteochondritis dissecans (M93.2)

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

current injury - see injury of knee and lower leg (S80-S89)
recurrent dislocation or subluxation of joints (M24.4)
recurrent dislocation or subluxation of patella (M22.0-M22.1)

Other codes that can never be billed with M23

These codes carry an Excludes1 note pointing at M23. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading M23 alone.

S83.2Tear of meniscus, current injury

Risk adjustment

M23 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead M23

8 child codes. Green means billable.

Questions about M23

Is M23 a billable ICD-10-CM code?: No. M23 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M23 sit in the tabular list?: Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Other joint disorders (M20-M25).
What cannot be coded together with M23?: M23 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.